Field of the Invention
The present invention relates to a high modulus glass fiber, a composition for producing the same, and a composite material comprising the same.
Description of the Related Art
Glass fiber is an inorganic fiber material that can be used to reinforce resins to produce composite materials with good performance. As a reinforcing base material for advanced composite materials, high-modulus glass fibers were originally used mainly in the aerospace industry or the national defense industry. With the progress of science and technology and the development of economy, high-modulus glass fibers have been widely used in civil and industrial fields such as wind blades, pressure vessels, offshore oil pipes and auto industry.
The original high-modulus glass compositions were based on an MgO—Al2O3—SiO2 system and a typical solution was S-2 glass of American company OC. The modulus of S-2 glass is 89-90 GPa; however, the production of this glass is excessively difficult, as its forming temperature is up to about 1571° C. and its liquidus temperature up to 1470° C. and therefore it is difficult to realize large-scale industrial production. Thus, OC stopped production of S-2 glass fiber and transferred its patent to American company AGY.
Thereafter, OC, developed HiPer-tex glass having a modulus of 87-89 GP, which were a trade-off for production scale by sacrificing some of the glass properties. However, as the design solution of HiPer-tex glass was just a simple improvement over that of S-2 glass, the forming temperature and liquidus temperature remained high, which causes difficulty in attenuating glass fiber and consequently in realizing large-scale industrial production. Therefore, OC also stopped production of HiPer-tex glass fiber and transferred its patent to the European company 3B.
French company Saint-Gobain developed R glass that is based on an MgO—CaO—Al2O3—SiO2 system, and its modulus is 86-89 GPa; however, the total contents of SiO2 and Al2O3 remain high in the traditional R glass, and there is no effective solution to improve the crystallization performance, as the ratio of Ca to Mg is inappropriately designed, thus causing difficulty in fiber formation as well as a great risk of crystallization, high surface tension and fining difficulty of molten glass. The forming temperature of the R glass reaches 1410° C. and its liquidus temperature up to 1350° C. All these have caused difficulty in effectively attenuating glass fiber and consequently in realizing large-scale industrial production.
In China, Nanjing Fiberglass Research & Design Institute developed an HS2 glass having a modulus of 84-87 GPa. It primarily contains SiO2, Al2O3 and MgO while also including certain amounts of Li2O, B2O3, CeO2 and Fe2O3. Its forming temperature is only 1245° C. and its liquidus temperature is 1320° C. Both temperatures are much lower than those of S glass. However, since its forming temperature is lower than its liquidus temperature, which is unfavorable for the control of glass fiber attenuation, the forming temperature has to be increased and specially-shaped tips have to be used to prevent a glass crystallization phenomenon from occurring in the fiber attenuation process. This causes difficulty in temperature control and also makes it difficult to realize large-scale industrial production.
In general, the above-mentioned prior art for producing high modulus glass fiber faces such difficulties as relatively high liquidus temperature, high crystallization rate, relatively high forming temperature, high surface tension of the glass, high difficulty in refining molten glass, and a narrow temperature range (ΔT) for fiber formation. Thus, the prior art generally fails to enable an effective large-scale production of high modulus glass fiber.